Today I had a strange problem when I wanted to define a DataTemplate of a specific type which is located in the same assembly as I wanted to use it.
The problem was that if I wrote the assembly-name in the import of the Namespace then I got the following Exception:

The type reference cannot find a public type named ‘MyType’

So after a few hours of testing and searching I finally found the solution. I just had to remove the assembly from the import of the namespace.